A hyper-frequency method enabling to
investigate into the bubble size distribution of a bubble cloud in which bubble radii are
lower than the equilibrium one is displayed. It is based on analysing the void rate
dissipation after the acoustic irradiation is switched off in terms of bubble dissolution.
The experimental evaluation of this method has been performed in air saturated water with
cavitation bubble cloud generated in a 308 kHz stationary acoustic field. The size
distributions achieve range from 19 μm to 59 μm and allow to follow the influences
of both the acoustic pressure and the irradiation duration on them. By taking into account
the bubble coalescences occurring during the bubble rise after the end of the acoustic
irradiation, the raw distributions have been qualitatively nuanced thanks to the exploitation
of a probabilistic model of free bubble coalescence.